Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)

Many of the major locomotor transitions during the evolution of Archosauria, the lineage including crocodiles and birds as well as extinct Dinosauria, were shifts from quadrupedalism to bipedalism (and vice versa). Those occurred within a continuum between more sprawling and erect modes of locomotio...

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Detalles Bibliográficos
Autores principales: Otero, Alejandro, Allen,Vivian, Pol, Diego, Hutchinson, John R.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2017
Materias:
Paleontología
Biomechanics
Bipedalism
Crocodylia
Dinosauria
Moment arm
Musculoskeletal model
Posture
Pronation
Quadrupedalism
Range of motion
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/87664
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-87664
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Paleontología
Biomechanics
Bipedalism
Crocodylia
Dinosauria
Moment arm
Musculoskeletal model
Posture
Pronation
Quadrupedalism
Range of motion
spellingShingle Paleontología
Biomechanics
Bipedalism
Crocodylia
Dinosauria
Moment arm
Musculoskeletal model
Posture
Pronation
Quadrupedalism
Range of motion
Otero, Alejandro
Allen,Vivian
Pol, Diego
Hutchinson, John R.
Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
topic_facet Paleontología
Biomechanics
Bipedalism
Crocodylia
Dinosauria
Moment arm
Musculoskeletal model
Posture
Pronation
Quadrupedalism
Range of motion
description Many of the major locomotor transitions during the evolution of Archosauria, the lineage including crocodiles and birds as well as extinct Dinosauria, were shifts from quadrupedalism to bipedalism (and vice versa). Those occurred within a continuum between more sprawling and erect modes of locomotion and involved drastic changes of limb anatomy and function in several lineages, including sauropodomorph dinosaurs. We present biomechanical computer models of two locomotor extremes within Archosauria in an analysis of joint ranges of motion and the moment arms of the major forelimb muscles in order to quantify biomechanical differences between more sprawling, pseudosuchian (represented the crocodile Crocodylus johnstoni) and more erect, dinosaurian (represented by the sauropodomorph Mussaurus patagonicus) modes of forelimb function. We compare these two locomotor extremes in terms of the reconstructed musculoskeletal anatomy, ranges of motion of the forelimb joints and the moment arm patterns of muscles across those ranges of joint motion. We reconstructed the threedimensional paths of 30 muscles acting around the shoulder, elbow and wrist joints. We explicitly evaluate how forelimb joint mobility and muscle actions may have changed with postural and anatomical alterations from basal archosaurs to early sauropodomorphs. We thus evaluate in which ways forelimb posture was correlated with muscle leverage, and how such differences fit into a broader evolutionary context (i.e. transition from sprawling quadrupedalism to erect bipedalism and then shifting to graviportal quadrupedalism). Our analysis reveals major differences of muscle actions between the more sprawling and erect models at the shoulder joint. These differences are related not only to the articular surfaces but also to the orientation of the scapula, in which extension/flexion movements in Crocodylus (e.g. protraction of the humerus) correspond to elevation/depression in Mussaurus. Muscle action is highly influenced by limb posture, more so than morphology. Habitual quadrupedalism in Mussaurus is not supported by our analysis of joint range of motion, which indicates that glenohumeral protraction was severely restricted. Additionally, some active pronation of the manus may have been possible in Mussaurus, allowing semi-pronation by a rearranging of the whole antebrachium (not the radius against the ulna, as previously thought) via long-axis rotation at the elbow joint. However, the muscles acting around this joint to actively pronate it may have been too weak to drive or maintain such orientations as opposed to a neutral position in between pronation and supination. Regardless, the origin of quadrupedalism in Sauropoda is not only linked to manus pronation but also to multiple shifts of forelimb morphology, allowing greater flexion movements of the glenohumeral joint and a more columnar forelimb posture.
format Articulo
Articulo
author Otero, Alejandro
Allen,Vivian
Pol, Diego
Hutchinson, John R.
author_facet Otero, Alejandro
Allen,Vivian
Pol, Diego
Hutchinson, John R.
author_sort Otero, Alejandro
title Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
title_short Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
title_full Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
title_fullStr Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
title_full_unstemmed Forelimb muscle and joint actions in Archosauria: Insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha)
title_sort forelimb muscle and joint actions in archosauria: insights from crocodylus johnstoni (pseudosuchia) and mussaurus patagonicus (sauropodomorpha)
publishDate 2017
url http://sedici.unlp.edu.ar/handle/10915/87664
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